a) \(\left(-\frac{3}{4}+\frac{2}{5}\right):\frac{3}{7}+\left(\frac{3}{5}+\frac{-9}{4}\right):\frac{3}{7}\) 

= \(\left(-\frac{3}{4}+\frac{2}{5}\right)\cdot\frac{7}{3}+\left(\frac{3}{5}+\frac{-9}{4}\right)\cdot\frac{7}{3}\)

= \(\left(-\frac{15}{20}+\frac{8}{20}\right)\cdot\frac{7}{3}+\left(\frac{12}{20}-\frac{45}{20}\right)\cdot\frac{7}{3}\)

= \(-\frac{7}{20}\cdot\frac{7}{3}-\frac{33}{20}\cdot\frac{7}{3}\)

=\(\frac{7}{3}\cdot\left(-\frac{7}{20}-\frac{33}{20}\right)\)

=\(\frac{7}{3}\cdot\left(-2\right)\)

=\(-\frac{14}{3}\)

a)

\(9^{8} = \left(\right. 3^{2} \left.\right)^{8} = 3^{16}\)

\(8^{9} = \left(\right. 2^{3} \left.\right)^{9} = 2^{27}\)

ta có:
\(3^{16} = 3. 3^{15} = 3 \left(\right. 3^{3} \left.\right)^{5} = 3.2 7^{5}\)

\(2^{27} = 2^{2} . 2^{25} = 4. \left(\right. 2^{5} \left.\right)^{5} = 4.3 2^{5}\)

⇒ \(3.2 7^{5} < 4.3 2^{5}\) nên \(3^{16} < 2^{27}\)

\(Vậy9^8<8^9\)

\(9^8<8^9\)

\(3^{39}<11^{20}\)

\(\frac{x-1}{9}=\frac{8}{3}\)

\(\left(x-1\right)\cdot3=8\cdot9\)

\(\left(x-1\right)\cdot3=72\)

\(x-1=\frac{72}{3}\)

\(x-1=24\)

\(x=24+1\)

\(x=25\)

\(\frac{x}{4}=\frac{18}{x+1}\)

\(x\cdot\left(x+1\right)=18\cdot4\)

\(x\left(x+1\right)=72\)

\(x\left(x+1\right)=8\cdot9\)

\(x=8\)

\(\frac{-x}{4}=\frac{-9}{x}\)

\(\frac{x}{-4}=\frac{-9}{x}\)

\(x\cdot x=\left(-9\right)\cdot\left(-4\right)\)

\(x^2=36\)

\(x^2=\left(-6\right)^2\)hoặc \(x^2=6^2\)

\(x=-6\)  hoặc\(x=6\)

a)x-1/9=24/9       =>  x-1=24 =>x=23

b)x(x+1)=18*4   =>x=8

c)-x:4=-9:x     =>-1.x²=-1.36    =>x=6

k mik nha!

a, Đặt A = 8¹⁰ - 8⁹ - 8⁸ = 8⁸.8² - 8⁸.8¹ - 8⁸.1 = 8⁸.(8² - 8¹ -1) = 8⁸.55

Vì 55 chia hết cho 55 nên 8⁸ chia hết cho 55 hay A chia hết cho 55.

b, Đặt B = 7⁶ + 7⁵ - 7⁴ = 7⁴.7² + 7⁴.7¹ + 7⁴.1 = 7⁴.(7² + 7¹ - 1) = 7⁴.55

Vì 55 chia hết cho 55 nên 7⁴.55 chia hết cho 55 hay B chia hết cho 55.

c, Đặt C = 81⁷ - 27⁹ - 9¹³ =  (3⁴)⁷ - (3³)⁹ - (3²)¹³ = 3²⁸ - 3²⁷ - 3²⁶ ( Đến dây thì tương tự như phần a bạn nhé)

d, Phần này cũng tương tự phần a. 

giup j zay bn

thiếu đề bạn ah

Ta có: 3636:(12x−91)=36

12x–91=3636:36

12x–91=101

12x=101+91

12x=192

x=192:12

x=16

Vậy x=16

440 + 2. (125 – x) = 546

2. (125 - x)=546 - 440

2. (125 - x)=106

125 - x=106 : 2

125 - x=53

x=125-53

x=72

bài 1b)

\(8\frac{1}{14}-6\frac37\)

C1:\(\frac{113}{14}-\frac{45}{7}\) =\(\frac{113}{14}-\frac{90}{14}=\frac{23}{14}\)

C2:\(8\frac{1}{14}-6\frac37=\left(8-6\right)+\left(\frac{1}{14}-\frac37\right)=2+\left(\frac{1}{14}-\frac{6}{14}\right)\)

\(=2+\frac{-5}{14}=\frac{28}{14}-\frac{5}{14}=\frac{23}{14}\)

bài 1 c)\(7-3\frac67\)

C1:\(\) \(7-3\frac67=7-\frac{27}{7}=\frac{49}{7}-\frac{27}{7}=\frac{22}{7}\)

C2:\(7-3\frac67=\left(7-3\right)-\frac67=4-\frac67=\frac{28}{7}-\frac67=\frac{22}{7}\)

a: \(3636:\left(12\cdot x-91\right)=36\)

=>\(12x-91=\frac{3636}{36}=101\)

=>12x=91+101=192

=>\(x=\frac{192}{12}=16\)

b: \(446+2\cdot\left(125-x\right)=546\)

=>\(2\left(125-x\right)=546-446=100\)

=>125-x=50

=>x=125-50=75

c: \(\left(x-36\right):18=10+2\)

=>\(\left(x-36\right):18=12\)

=>\(x-36=18\cdot12=216\)

=>x=216+36=252

Bài 1:

\(A=\frac{\frac{1}{12}-\frac{2}{9}-1}{\frac{5}{18}+\frac{-3}{4}-\frac{1}{9}}\)

\(A=\frac{\frac{1}{12}-\frac{2}{9}-\frac{18}{18}}{\frac{5}{18}+\frac{9}{12}-\frac{1}{9}}\)

\(A=\frac{1}{3}-\frac{18}{5}\)\(A=\frac{5}{15}-\frac{54}{15}\)

\(A=\frac{-49}{15}\)